ADV7511 operating in DVI Mode

Hi,

I have a Xilinx KC705 dev-board, I'm currently attempting to drive an FPGA generated chequered test pattern through the ADV7511 as DVI.

I can drive the test pattern as a HDMI image without any issue, I change the following registers:-

0xAF = 0x04

0x18 = 0x86 (Also tried varying the CSC scaling factor bits 7:5)

0xD5 = 0x02

With these changes, I can view the test pattern but the chequer colours do not appear the same as they do for the HDMI. There does not seem to be as much range of colour. The CSC values I've left as default. 

Is there anything else that needs setting in order to view the image as DVI?

many thanks.

glw